The present invention relates to a method of filling liquid into a high-temperature and high-pressure vessel and to an apparatus therefor, said method and said apparatus being used, for example, to fill a liquid into a reactor or a steam generator which causes generation of a high-temperature and high-pressure steam.
Conventionally, an emergency cooling apparatus for reactor core which is based on the use of a static means includes, as a first prior art, one which is disclosed in Japanese Patent Unexamined Publication No. 60-235092. In the emergency cooling apparatus disclosed in this document at the time when a loss-of-coolant accident has taken place due to, for example, breakage of reactor pipings, the pressure within a water storage tank disposed at a level higher than that corresponding to a pressure vessel of the reactor is equalized with the pressure within the latter. The coolant within the water storage tank is thereby supplied into the pressure vessel by the action of the gravitational force.
More specifically, a first piping having a first valve at a midway thereof connects a top section of the reactor pressure vessel and a top section of the water storage tank. A second piping having a second valve at a midway thereof connects a bottom of the water storage tank and the reactor pressure vessel. A differential pressure gage is provided on a piping communicating an upper section of the reactor pressure vessel with an upper section of the water storage tank. Where a loss-of-coolant accident has occurred, the first valve is opened. As a result, the steam generated within the pressure vessel is led to a position above the water surface of the water storage tank by way of the first piping. Thus, the pressures within the pressure vessel and within the water storage tank are equalized with each other while both are being monitored by the differential pressure gage. Thereafter, the second valve is opened. In consequence, the water within the water storage tank is filled into the pressure vessel by utilizing the gravitational force. This type of liquid filling apparatus is disclosed in Japanese Patent Unexamined Publications Nos. 57-69289, 62-212594 and 60-259995.
A second prior art is disclosed in Japanese Patent Unexamined Publication No. 62-170886. In this Publication, a reactor container is provided in a state wherein it stores a pressure vessel therein and another upper reactor container is added thereto at a position higher than that corresponding to said pressure vessel. At the time when a loss-of-coolant accident has taken place, the suppression pool water within the pressure vessel of the lower reactor container is pressure fed to the upper reactor container by utilizing the increased pressure within the pressure vessel. The suppression pool water is stored in the upper reactor container as a coolant. Thereafter, a spray system within the lower reactor container is caused to operate so as to condense the steam within the same. During this spraying operation, the pressure within the lower reactor container is decreased. Thereafter, the coolant as above stored is filled from the upper reactor container into the lower one by the gravitational force. By repetition of this operation, the reactor core within the pressure vessel of the lower reactor container is cooled. When the coolant within the upper reactor container is exhausted, a rise in pressure within the reactor container is waited while, for example, the operation of the spray system is kept stopped. Thereafter, the suppression pool water within the reactor container is pressure fed again to the upper reactor container. The reactor core within the pressure vessel of the lower reactor container is cooled through repetition of the above operation.
According to the first prior art, upon completion of filling into the pressure vessel the amount of the coolant as stored in the water storage tank, any further filling of coolant becomes impossible. Accordingly, the first prior art is unsuitable for a long period filling of coolant.
According to the second prior art, the pressure within the pressure vessel of the reactor is forcedly decreased by operation of the spray system and, only when that pressure has been decreased, the coolant as stored in the upper reactor container is filled into the pressure vessel of the reactor by the action of the gravitational force. For this reason, a large amount of time is required until the filling of the coolant into the pressure vessel is started. In addition, it is premised that the operation of the spray system is secured, so that the coolant filling must rely upon the normality of movable section such as a pump motor for the spray system. Accordingly, not a static means but a dynamic means is inevitably employed in substance.
Furthermore, where the pressure equalizing means of the first prior art is adopted in the second prior art, the coolant can be expected to be more speedily filled into the pressure vessel. However, only the use of the pressure within the suppression pool within the lower reactor container fails, from the standpoint of pressure balance, to cause the pool water to be fed to the interior of the upper reactor container, whose pressure has been increased by the pressure equalizing means, and thus stored again in the same. Re-filling of coolant, therefore, is not smoothly effected.